GG101 Final Exam Review

  Final Exam info:   Tuesday, December 15th 12-2pm   100 multiple choice/true-false questions   Covers material from all lectures (comprehensive)   1 hand-written page “cheat sheet” allowed (double-sided ok)   Things to help you study:

1. Lecture notes (posted on web) 2. Old midterms and practice exams (posted on web) 3. Homework assignment questions 4. Assigned reading

Class Website http://www.soest.hawaii.edu/GG/FACULTY/smithkonter/GG_101/

Our Solar System Consists Of: •  1 unordinary star •  8 classical planets •  5 dwarf planets •  240+ known satellites (moons) •  Millions of comets and asteroids •  Countless particles; and interplanetary space

Earth, the Sun, and other objects in the Solar System originated at the same time from the same source and have

evolved in varying ways since then

Our Sun • Solar core is site of

nuclear fusion.

• H is converted to He, which has less mass.

• Mass differential is expelled as energy (light and heat).

• The Sun is getting “lighter” through time.

• The Sun has enough fuel to last another 4 to 5 billion years.

Mercury Venus Earth Mars

Terrestrial Planets

Main components: O, Fe, Si, Mg, Ca, K, Na, Al

Terrestrial planets are small and rocky, with thin atmospheres, silicate & metallic shells.

Jupiter Saturn

Uranus Neptune

Gas Giant planets are massive with thick atmospheres. Main components: He, H, CO2, H2O, N2, NH3, CH4

Gas Giant Planets

Early Heat Within The Earth Early Earth began to heat as the last collisions subsided

1. Initial heat from impacts (bombardment) 2. Collisions produced heat that was stored (rock good insulator) 3. Radioactivity 4. Gravitational contraction

•  Iron mixed with nickel, oxygen – metallic •  3500 km thick

•  Outer core: liquid; convects heat & generates a magnetic field

•  Inner core: solid; over 4,300°C

Earth’s Core

Iron-nickel

•  Fluid motion of liquid iron in the outer core generates Earth’s magnetic field

  Made of solid rock: Silicate (silicon + oxygen)   2900 km thick   Moves heat around through convection   Mantle rock also deforms as a fluid

Like Silly Putty, behaves as a: Solid – over short time Fluid – over long time

Earth’s Mantle

Continental Crust (~35 km thick)   Formed early in Earth’s history   Rocks less dense than mantle rocks   Is essentially “floating” on the mantle

Oceanic Crust (~7 km thick)   Is currently being formed   Is denser than continental crust (more iron +

magnesium)

Like floating ice extends deeply below water level

Earth’s Crust granite

basalt

What is a Mineral?

•  natural occurrence •  inorganic •  solid

•  has a crystalline structure* •  has a definite chemical composition*

Minerals are natural, inorganic, solid crystalline compounds with a definite (but variable) chemical composition

Olivine (Mg,Fe)2SiO4

Halite (NaCl)

Ice (H2O) Copper (Cu)

Gypsum (CaSO4)-2(H2O)

Pyrite (FeS2)

Minerals

Fool’s Gold Salt

Silicates (Si + O) •  Si & O are most common elements •  Fundamental unit: silicate tetrahedron (4-sided pyramid)

•  -1 Si + 4 O atoms

Si

O

O O O

Garnet: high temp & pressure

Under special conditions, rare silicates may crystallize

Most silicates are formed from cooling magma.

Carbonates   Contain carbonate anion (CO3)-2

  Form in waters saturated by calcium (oceans) and as a result of biological processes

  Examples: calcite CaCO3 --> limestone

limestone Calcite is calcium carbonate

Fundamental Rock Types   Igneous Rocks: form when magma solidifies

  Sedimentary Rocks: form when sediment becomes cemented into solid rock

  Metamorphic rocks: form when heat, pressure, or hot water alter any preexisting rock

Types of Igneous Rocks   Extrusive (volcanic) - forms when magma erupts & solidifies on the surface

  Intrusive (plutonic) - forms when magma solidifies within the crust

Extrusive Igneous Rocks   Lava: fluid magma that flows from a crack or volcano onto Earth’s surface

  Magma cools quickly = less time for crystals to form

  Ex.: Basalt - common volcanic rock, ocean crust, few crystals

Porphyric rock

Obsidian

Basalt

Lava

Rhyolite

Composition: assemblage of minerals (Si vs. Mg)

Texture: size and arrangement of crystals (cooling history)

Igneous rocks are classified based on their composition and texture

Composition

Text

ure

The Major 7 Types of Igneous Rocks

Composition Types

  Felsic: Feldspar & Silica Granite (large grains), Rhyolite (small)

  Mafic: Magnesium & Iron (Fe) Gabbro (large), Basalt (small)

  Ultramafic: High Mg & Fe Peridotite (mantle material, rare)

  Intermediate: Andesite

Felsic Mafic

Ultramafic

Andesite

Weathering   Def.: processes that decompose rocks & convert

them to loose gravel, sand, clay, & soil

  Three primary types:  Physical Biological  Chemical

Arches Nat’l Park,!Utah!

Types of Physical Weathering  Pressure-release fracturing  Abrasion  Freeze-Thaw (frost wedging)  Hydraulic Action  Growth of Salts

Sedimentary Rocks

  Generally, made from older rocks   Make up only ~5% of Earth’s crust, but…..   Make up 75% of all rocks exposed at the

surface

Why Study Sedimentary Rocks?

•  Reflect physical and chemical characteristics of source environments

•  Contain direct and indirect evidence of life

•  Can be interpreted to recreate Earth history

•  Source of “fossil fuels”

Sedimentary Rock Types

  Clastic – broken down rocks (clasts) Ex.: sandstone

  Chemical – directly ! precipitates out of water! Ex.: rock salt!

  Biogenic – remains of living ! organisms! ! ! ! ! !! Ex.: limestone, chalk, coal!

rock salt rock gypsum limestone

travertine

micrite dolostone

chert

Types: Chemical Sedimentary Rocks!

  Lithification of “organic” (plants, etc.) material   Ex.: Coal is formed from preserved plant material in

swamps

Types: Biogenic Sedimentary Rocks!

coal! chert!

Coal swamp forest!

Metamorphic Rocks   Metamorphism: process of rising temperature & pressure, or changing chemical conditions, that transforms rocks &

minerals

  Ways: 1. Heat 2. Pressure 3. Fluid activity

Metamorphism tells us a rock’s tectonic history

slate

phyllite schist

gneiss

Metamorphic Grade

Types of Metamorphism

 Contact

 Regional

 Hydrothermal

separate processes, but can happen @ same time

  when magma comes in contact with basement rock at shallow depth and heats it up

  magma also brings reactive fluids

Contact Metamorphism

  When major crustal movements build mountains and deform rocks

  Rocks deformed & heated at same time

Regional Metamorphism

regional metamorphism

Hydrothermal Metamorphism

Basalt

Serpentinite

Water

• Heat and pressure release chemically active fluids from rocks. • These fluids transport heat, ions dissolve in hot water • Reactions promote recrystallization

  Slates

  Phyllite

  Schists

  Gneisses

Common Metamorphic Rocks

New seafloor is being created as the seafloor spreads.

The continents move apart as new seafloor expands the ocean basin

The magnetic field is "frozen" in the newly-created seafloor.

Normal magnetic field

Reversed magnetic field

Normal magnetic field

• Oceanic crust preserves a record of Earth’s magnetic polarity at the time the crust formed

Ma = Million years ago

• Seafloor ages vary from 0 to ~160 Ma with a distinctive pattern

• Oldest seafloor is much younger than most of continental crust

1 billion years = 1 Gyr 1 million years = 1 Myr 1 thousand years = 1 kyr

• Age of the Earth: 4.5 Gyr

• Oldest continent rocks: 3.8 Gyr

• Youngest continent rocks: 250 Myr

Time span (billions of years ago) 0.25 to 0

0.7 to 0.25 1.7 to 0.7

2.5 to 1.7

3.8 to 2.5

2.5 to 0.7

3.8 to 1.7

Three types of plate boundaries

•  Divergent (move apart)

•  Convergent (come together)

•  Transform (move side by side)

Divergent Boundary

As two plates continue to move apart, the rock in the seafloor grows older as its distance from the rift zone increases

• Plates collide • Subduction zones • We observe: 1) Trench 2) Volcanoes 3) Earthquakes

1 2

3

- Sumatran Coast

- Alaskan Coast

• Examples - Peru-Chilean Coast

• Plates slide by • Transform faults • We observe: 1) Offset surface features 2) Earthquakes

• Examples - San Andreas Fault

strike-slip faulting

- North Anatolian Fault (Turkey)

Fig.4.20

- sometimes marked by chain of islands -  less common than plate-boundary volcanoes - different composition (deep source)

hot spot trail

Three Common Types of Magma:

Basaltic lava flows easily because of its low viscosity and low gas content.

The low viscosity is due to low silica content.

Aa - rough, fragmented lava blocks called “clinker”

Pahoehoe - smooth, shiny, and ropy surface

BASALTIC

Mount St. Helens, 1980

•  Erupts explosively because it has high gas content

•  It is viscous and therefore traps gas.

•  High viscosity is related to high silica content

ANDESITIC

Three Common Types of Magma:

Rhyolitic lava flow •  Erupts catastrophically because it has high gas content.

•  It is viscous and therefore traps gas, builds pressure and explosively erupts.

•  High viscosity high silica content

RHYOLITIC

Three Common Types of Magma:

Shield Volcano •  Low silica, low gas magma originates in the mantle. •  Fluid, basaltic lava results in “Aa” and “Pahoehoe”. •  Low viscosity creates broad, gentle slopes. •  Phreatomagmatic eruptions occur when lava contacts water

(rapid expansion of steam) .

3 Types of Mountains

Volcanic Mountains: Built by accumulation of volcanic materials

Fold and Thrust Belts: Built by compression stresses

Fault Block Mountains: Built by extensional stresses

Stress can be:

  Tensional (stretching)   Compressive (shortening)   Shear (side-to-side)

Major Types of Faults

Dip- Slip Faults

Strike- Slip Faults

Dip-Slip and Strike-Slip faults

Fold and Thrust Mountains

•  Collision of India with Eurasia caused compressive stresses.

•  These stresses raised the Himalayas and Tibet. The Himalayas

Fault Block Mountains: Tensional Stresses

Elastic Rebound Theory Earthquakes result from slow buildup of elastic strain, and its sudden release – like bending a ruler until it breaks.

What Are Earthquakes?

2. Surface Waves: travel along the outer layer of the crust (Love and Raleigh)

- Ground rolls like a water wave - Waves travel slowly and cause the most damage.

Two Types of Seismic Waves

1. Body Waves: travel through the body of the Earth (P & S)

- Waves compress and pull rocks in the direction of movement, - Change the volume & shape of material

Traveling S- and P-

waves through

the Earth.

P-waves

S-waves

S-waves

Tsunamis are NOT tidal waves

Underwater fault

1.

BIG earthquake

2.

Tsunami generated

3.

Tsunamis are seismic sea waves caused by earthquakes, landslides, eruptions of island

volcanoes.

How old is that rock?

  Relative age: order of events

  Absolute age: age in years

Relative dating tells us what order things happened, but not how many years ago they happened.

Radioactive Half-Life   Def.: time it takes for 1/2 of radioactive atoms in a

sample to decay

  “Parent” decays to “daughter”

  Potassium-40 half-life = 1.3 billion years

(potassium-40) (argon-40)

The Greenhouse Effect Determines Earth’s Heat Budget

Greenhouse Gases Carbon Dioxide: Most abundant, long-lived Methane: Powerful greenhouse gas, short-lived CFCs: Being phased out Ozone: Very short lived Nitrous Oxide: Increasing

The Ice Ages •  Caused by changes in solar radiation •  Changes in atmospheric carbon dioxide were caused by the temperature changes.

Earth’s atmospheric temperature has risen by about 0.9°C in the past 100 years.

- Atmospheric CO2 is greater now than it ever has been in the past ? Yrs - Earth is warmer now than at any time in the past 1,300 years.

Global Sea Level Rise

A glacier is a river of ice. Glaciers can range in size from: 100s of m (mountain glaciers) to 100s of km (continental ice sheets)

Most glaciers are 1000s to 100,000s of years old!

Total Water Fresh Water Oceans 96.6% Ice 1.7% 69.6% Groundwater 1.7% 30.1% (more than half is salty) Rivers & Lakes 0.007% 0.27%

Groundwater is found where the crust is porous (empty space in a rock)

Groundwater flows in response to gravity and hydraulic pressure

Velocity of flow ranges from m/day to cm/century   Depends on pressure gradient (slope of water table)   Depends on permeability of the rocks

High Pressure

Low Pressure

The coastal zone is a dynamic environment that is constantly changing

Coastal processes are driven by: wind, waves, tides, sea-level change, & currents

•  Gravity and Earth’s rotation create two tides every day

Lunar Tide

•  Gravitational pull from the Moon

Five Recognized Oceans Average ocean depth is 3800 m (about the length of Manoa Valley)

Surface Currents   Driven by prevailing winds   The Coriolis Effect turns currents right in the north and left in the south   Circulation forms 5 Gyres in the ocean basins   The gyres circulate heat.

Ocean Currents

Continental Shelf: the flat, submerged edges of continents Continental Slope: the sloping edges of continental shelf Continental Rise: transition from continental to oceanic crust

The Continental Margin

Slide by J. Sinton

Nu‘uanu landslide ~ 2 Million years ago

Big gap in flank, large “bumps” on the seafloor

Largest (Tuscaloosa) is multiple miles across, >> thousand ft tall

Debris stretches nearly 100 miles

(Moore et al. 1989)

17 large landslides in principal Hawai‘i region

Represents ~6 million yrs (= 1 every 350,000 yrs)

Two Kinds:

1. slumps (prolonged, progressive formation)

2. catastrophic debris avalanches

Debris avalanches are likely to produce huge tsunami

locally, but Would tsunami be Pacific-

wide?

Other landslides around the islands

GG101 Final Exam Review

  Final Exam info:   Tuesday, December 15th 12-2pm   100 multiple choice/true-false questions   Covers material from all lectures (comprehensive)   1 hand-written page “cheat sheet” allowed (double-sided ok)   Things to help you study:

1. Lecture notes (posted on web) 2. Old midterms and practice exams (posted on web) 3. Homework assignment questions 4. Assigned reading